Electron beam lithography apparatuses that perform lithography using an electron beam as an exposure beam are widely applied to master producing apparatuses for optical discs such as digital versatile discs (DVDs) and Blu-ray discs and large capacity discs such as magnetically recording hard discs, and are also used in producing record media referred to as discrete track media or patterned media.
When a master for the above-described discs or the like is produced using the electron beam lithography apparatus, a resist layer is formed on the recording surface of a substrate that is to become a master disc, and control is performed such that by making the substrate rotate and simultaneously move translationally so as to relatively move a beam spot in a radial direction and in a tangential direction with respect to a substrate drawing surface as needed, spiral-like or concentric tracks are drawn on the substrate drawing surface to form latent images in the resist.
In the electron beam lithography apparatus, the electron optical system for the electron beam and the electron column housing the electron optical system therein vibrate due to vibrations of the stage for the translational movement of the substrate and the rotation drive system, or vibrations caused by external disturbance or the like. The irradiation position of the electron beam on the substrate drawing surface also fluctuates due to these vibrations, and hence the irradiation position fluctuation caused by the electron beam irradiating system needs to be corrected for. Further, because an irradiation position error occurs due to a driving mechanism system for the stage, that is, a rotation drive and translation drive (feed drive) system for the stage on which a substrate is mounted, the mechanism system position error needs to be corrected for.
As a beam position fluctuation measuring method used for this correction, there is a technique described in, for example, Patent Reference 1 as in the following. In this reference, a beam current detector (Faraday cup), which has been moved immediately below the aperture on the optical axis of the ion beam optical system in measurement, is used to measure beam position fluctuation from change in the amount of current thereof (a fixed method). However, beam position fluctuation data is collected before record data is drawn, and hence beam position fluctuation when being actually drawn may be different from beam position fluctuation at the measurement. Further, the correction signal is limited in frequency to a specific frequency component because a correcting signal is stored in a memory.
Yet further, correction is performed by deflecting the beam in an opposite direction to the fluctuation while a waveform stored in a memory is output synchronously with the specific frequency, when drawing (recording) on a substrate (a master). Thus, there is a problem that the correction effect is small since the correction is performed by feed-forward control.
Further, position errors due to the mechanism system are measured while drawing, and correction is performed by deflecting the electron beam based on the mechanism system position errors. The measurement of the mechanism system position errors and the beam irradiation position correction are described in, for example, Patent References 2, 3 as in the following.
As described above, the electron beam irradiation position fluctuates due to the electron beam irradiating system and the mechanism system. Conventionally, it is difficult to correct for this composite irradiation position error sufficiently accurately. In particular, in applying to large capacity discs such as hard discs, of which even higher density drawing by an electron beam having a very small beam spot is desired, as described above, highly accurate control of the electron beam irradiation position is crucially important.
Patent Reference 1: Japanese Patent Application Laid-Open Publication No. H08-212950 (p. 3, FIG. 2)
Patent Reference 2: Japanese Patent Application Laid-Open Publication No. H10-180073
Patent Reference 3: Japanese Patent Application Laid-Open Publication No. 1997-190651